89 cherokee with issues...

[metalmegs]

i have an 89 cherokee pioneer with a 4.0L I6 manual and recently it started acting up. by acting up i mean that while i'm driving at any speed the rpms drop (usually about 500rpms) or sometimes the tac will jump around (2000rpms down to 0 then back up and down again) and the jeep will stall for a second or two. at slower speeds (15-25mph) sometimes it will kill itself all together rather than just stalling. i've also noticed that the oil pressure drops a little when it's doing this. i just give it some gas and it's fine, for a few minutes til it starts up again. i've had the jeep for only about three months, but the previous owner claimed that it was well-maintained.

my boyfriend and his dad have put in a new thermostat and water pump and have also flushed the radiator. they determined that part of the problem was that the t-stat was shot and it was overheating on me telling the computer to shut the engine off (even while i was driving) the new water pump also helped. however, it is still "acting up", but it's not overheating so much anymore.

i was just wondering if anyone could help me with figuring out why the tac is jumping around so much and stalling/killing itself on me.

[ops5]

Maybe something with the Throttle position sensor, or some other similar componet

[Saudade]

Overheating can cause the engine to shutdown but it won't start until it's cooled off enough.

I would check th fuel system. How much gas do you have in the tank when this happens? Have you run out of gas recently?

[Stick89]

Bout 2 mo ago,my 89' was goin bout 2 blks and then it would start stutterin,misfiring,yadda yadda yadda......gremlin was the fuel filter.
I'm not too sure about everbody elses,but my 89'runs like crap on gasoline with anything lower than a 93 octane rating....Make sure you keep an eye on the injectors to.
One other thing,if you have the "CLOSED"cooling system,toss that sucker and get a GDI 3 core rad..with a real radiator cap

[metalmegs]

i was at about a quarter of a tank when it happened and had been driving a two and half hour drive. thus the major overheating. we figured it was the fuel filter some something similar but just haven't had the time to really check it out yet.

[4x4grey88]

There is a Crank Shaft Indicator just on top of the bell housing. It measures the RPMS of your engine and tells the computer. Like the Throttle Position Sensor tells the computer the postion of your throttle (how much gas your giving it). Which also computes the idle.

I would recommend that you change out both and then reset your computer.

To reset your computer, remove the positive (+) lead from the battery and turn (and hold for 10 seconds) your ignition (key) on and off a couple times. Replace the positive lead and start you engine.

It might cost you just under $200.00 but it will show a difference right away.